Sequestration and utilization of carbon dioxide to improve engineering properties of cement-based construction materials with recycled brick powder: a pathway for cleaner construction
Pitabash Sahoo, Ashutosh Dwivedi, Shivkumar M. Tuppad, Souradeep Gupta
Abstract
The research explores the possibility of utilizing carbon dioxide to modify the properties of recycled brick powder (RBP) and enhance the engineering performances of RBP-mortar. The RBP, crushed to the size range of 0.075 to 4 mm, is carbonated by exposing to 5% CO 2 for 4 h and characterized for phase composition, porosity and micro-structure. The non-carbonated RBP (RBP) and pre-carbonated RBP (Carb-RBP) are applied to replace 25% and 75% of manufactured sand (M-sand) in cement mortars maintained at similar flow level (110 – 113%), which are then cured under three conditions - (i) ambient condition (N), (ii) 4 h of steam curing followed by moist and dry curing (STC), and (iii) accelerated CO 2 curing (5% CO 2 of 99% purity) for 4 h followed by moist curing and dry curing (CC). Physico-chemical characterizations suggest that Carb-RBP has higher micro-pore volume and surface area contributed by pores in the size range of 1 nm to 3 nm than RBP. After carbonation, the reactivity of RBP in alkaline environment is increased due to CO 2 -induced breakdown of calcium and alumino-silicate minerals into calcium carbonate and silica gel. Due to addition of 25% and 75% RBP and Carb-RBP, hydration kinetics is accelerated by 4 – 4.50 h compared to control due to nucleation of hydration products on the surfaces of RBP. Faster precipitation of hydration products, more micro-pore sites in RBP and higher porosity due to increased water demand enhance the carbon sequestration in RBP-mortars and Carb-RBP mortars by 30–82% compared to control (0% RBP). Use of Carb-RBP to replace 25% of M-sand offer similar compressive strength as control and 19 – 21% higher strength than mortars with RBP (non-carbonated). CO 2 curing also reduces the total shrinkage of mortars with recycled brick powder by 12 – 17% compared to ambient curing and steam curing due to densification by calcium carbonate crystals. The findings from this research strongly suggests a significant reduction in embodied carbon of Portland cement-based construction materials by utilizing a combined approach of carbon sequestration and replacement of fine aggregates by recycled brick powder.